The invention relates to a device for axially conveying body fluids.
In particular, body fluids such as blood which can undergo irreversible changes caused by an energy input, such as in the case of emulsions and dispersions, can run into instable ranges in a disadvantageous manner when being conveyed in corresponding devices such as pumps.
Blood is a particularly sensitive fluid system. This opaque red body fluid of the vertebrates circulates in a self-enclosed vessel system where rhythmic contractions of the heart press the blood into various areas of the organism. In this case, the blood transports the respiratory gases oxygen and carbon dioxide as well as nutrients, metabolic-products and endogenous active ingredients. The blood vessel system including the heart is hermetically isolated from the environment so that, in a healthy organism, the blood does not undergo any changes when it is pumped through the body by way of the heart.
It is known that, when blood comes into contact with non-endogenous materials or as a result of the effect of energy from an external source, it has a tendency to hemolysis and clot formation. Clot formation can be fatal for the organism because it can lead to blockage in the extensive branching profile of the vessel system. Hemolysis describes the condition where the red blood cells are destroyed within the body beyond the physiological dimension.
The causes for hemolysis can be of a mechanical or metabolic nature. Increased hemolysis causes multiple organ damage and can lead to a person's death.
On the other hand it is evident that it is possible in principle, under certain prerequisites with reference to constructive aspects, to support the pumping capacity of the heart or even to replace the natural heart with a synthetic one. However, a continuous operation of implanted heart supporting systems or synthetic hearts is presently only possible with certain limitations heart supporting systems or synthetic hearts is presently only possible with certain limitations because the interactive effects of these artificial products with the blood and the entire organism still always lead to disadvantageous changes of the blood and the organism.
In the state of the art, axial blood pumps are known which mainly consist of a cylindrical tube in which a conveying part, which is executed as an externally located motor stator, is located. The rotor which is provided with a so-called blading, conveys the fluid in an axial direction after it has been made to rotate by means of the motor stator.
In the WO 00/64030 a device for the protective conveying of single- or multiple-phase fluids is described. Where this device is concerned, and in the direction of flow, an inlet guide facility is arranged upstream of the conveying part (rotor) and, as seen in the direction of flow, an inlet guide facility is arranged upstream of the conveying part (rotor) and, as seen in the direction of flow, an outlet guide facility is arranged downstream of the conveying part. Even though the blood in the flow passage zone of the pump does not undergo essentially any disadvantageous changes, the disadvantage is evident to the extent that, in the inflow zone upstream of the inlet guide facility and in the outflow zone downstream of the outlet guide facility of the pump, disrupted flows can form which can lead to a change of the blood.
In the U.S. Pat. No. 4,994,078 a heart pump is described whose outlet and inlet zones have certain flow cross-sections which are characterised by cross-sectional reductions and expansions, respectively. However, this flow pattern of the blood indicated at that location is only inadequately illustrated so that, in the outflow zone, it is not clearly recognisable how the blood flow is conducted further.
The invention is based on the task assignment of executing the inflow zone and the outflow zone of an axial pump in such a way that no flow separation occurs with an envisaged deflection of the flow in these zones, but instead a non-disrupted flow profile remains upheld to the greatest extent.